1. Field of the Invention
The present invention relates generally to a novel method and apparatus for operating a filter arrangement and, more particularly, to a method and apparatus of the kind capable of operating a filter arrangement as a function of contamination of, or particle suspension in, a fluid medium, such as, for instance, the water in a swimming pool. In this connection, the invention seeks to provide, while reducing electric energy consumption to between 30% and 60% of the energy used by conventional equipment, water of as good and constant a quality as regards hygienics or sanitation, safety and appearance as is obtained by the use of conventional systems. The teachings of the invention may be applied to existing equipment as well as to new pools.
2. The State of the Art
To comply with legal sanitation standards, public and private swimming pools are required to be equipped with controllable filter arrangements.
In some countries, such as Germany, treatment and disinfection of swimming pool water is governed by certain normative regulations, such as, for instance, DIN 19,643. Similar standards are mandated by law or regulation in other countries. The pool water is mechanically and chemically treated in a closed-loop system by being first removed and, following treatment, returned to the pool.
For this purpose, equipment is provided which ensures a constant quality of good water in a swimming pool which satisfies hygienic or sanitation standards, safety and appearance, to avoid human health hazards, as by spreading organisms causing diseases.
The filter arrangement is the major component and the main consumer of energy in such equipment; for not only does it provide for filtering of the water, but it also serves constantly to recirculate the water.
For such recirculation and filtering, electrically driven pumps are provided which are sized, for instance, pursuant to DIN 19,634 to accommodate the pipe and filter systems of the pool.
The requisite flow rate is determined on the basis of the applicable dimensions and other specifications, in dependence of
the water surface of the pool; PA1 the water surface per person; PA1 the frequency at which the pool is used by each person; PA1 the pollution caused by each person; and PA1 the type of pool. PA1 the flow resistance of pipes and armatures; PA1 the flow resistance of the filter; and PA1 the dynamic resistance of the filter as a result of its increasing congestion have to be taken into consideration.
In addition,
Those parameters determine the dimensions of the filter set-up, and ideally they will have been determined or defined prior to the construction of the pool. Its components will then ensure the constancy of the flow rate mandated by DIN 19 643, for example, regardless of the number of persons using the pool, even though the number is a decisive factor in calculating the flow rate.
Filter arrangements equipped with two and more pumps offer the possibility of saving electrical energy by selectively shutting down one or more of the pumps. Such a system would, however, be subject to the subjective competency and discretion of personnel in charge of the pool and, therefore, requires increased attention.
Furthermore, methods and apparatus are known which are designed to satisfy norms or standards by appropriately recirculating pool water.
German published patent specification DE-OS 26 45 183 discloses an electric motor pump drive for a water recirculation system. The motor is equipped with two stator coils which, by selective energization, allow the motor to operate at two different speeds and, hence, outputs of the pump.
While other switching arrangements may conceivably be provided as well, the disclosed motor is switched between its different speeds by signals from a sensor measuring the degree of turbidity of the water. The sensor may be mounted in the pipe system of the filter or in the pool. Since the output of the pump--not counting zero output when the pump is idle--can only be set at two different levels, such a system is not adaptable to operate continuously as a function of dynamically changing water conditions.
The lower output is said to lead to a reduced noise level. Also, adjusting the output of the pump in accordance with the degree of turbidity of the water cannot lead to satisfactory results, in view of the fact that the sensor or probe for measuring the turbidity responds also to higher levels of contamination if it is mounted within the filter pipe system. This would lead to an undesirable excess of chemicals in the water.
Mounting it within the pool subjects the probe to the likelihood of damage, unless it is mounted in a recess or cavity. However, nothing is disclosed by the reference as regards a position for the mounting of the sensor. But even if the sensor were to be mounted in a cavity, the likelihood of excessive chemicals in the water remains.
German patent 3,730,220 discloses a method of detecting the degree of contamination of water while the pool is in use.
The method requires water to be taken from the pool at a predetermined location from below the water surface where usually the turbidity is highest, regardless of the effect of higher contamination levels.
The sensor directly transforms the degree of water turbidity into a proportional output signal on the basis of which the output of the pump is controlled and continually adjusted to prevalent conditions. The output of the pump is thus automatically adjusted in proportion to the turbidity of the water caused by contamination, so that at increased turbidity, for instance, the rate of recirculation flow of the water is increased to provide for quicker cleaning of the water.
The known methods and the apparatus for practicing them are all based upon preset parameters which determine and limit the efficacy and economy of these methods and their control components.